This invention is directed to a waterbased coating composition and in particular to a waterbased coating containing a methylol (meth)acrylamide acrylic polymer and an acrylic hydrosol.
Methylol (meth)acrylamide acrylic polymers are polymers containing polymerized monomers of methylol methacrylamide or methylol acrylamide or any mixtures thereof.
Water based coating compositions useful for base coats and clear coats for automotive applications are shown in Wilfinger et al U.S. Pat. No. 4,730,020, issued Mar. 8, 1988. Waterbased coating compositions containing hydrosols are shown in Cowles et al U.S. Pat. No. 4,797,444 issued Jan. 10, 1989, Aluotto et al U.S. Pat. No. 4,477,609 issued Oct. 16, 1984. The preparation of acrylic hydrosols is shown in Hoefer et al U.S. Pat. No. 4,623,695 issued Nov. 18, 1986. However, none of the compositions shown in the art form finishes having properties that are required in particular for finishing or repair of exterior finishes of automobiles and trucks.
To date, solvent based finishes have been used to repair and refinish the exterior of automobiles and trucks. Finishes of these solvent based compositions provided the required color match, cured at ambient temperatures, had excellent adhesion to the substrate and gave properties such as gloss, hardness, distinctness of image required for the exterior of automobiles and trucks. To reduce solvent emissions, waterbased paints were suggested for use. However, none of the known water based paints form finishes that have the necessary properties for automotive and truck use.
Waterbased color coat for color coat/clear coat finish, i.e., a finish having a pigmented colored layer and a top clear layer, for automobiles and trucks now is coming into use for the manufacturing of original equipment. To repair such a finish, it would be very desirable and usually necessary to use a waterbased finish to match the original color particularly when metallic flake pigments are present in the color coat.